The present invention relates to a floatable aircraft such as a parachute balloon having an envelope in the shape of a balloon or airship capable of folding and being easily stored during periods of nonuse.
The above referred balloon or airship envelope can be collapsed and and stored while not in use, and combines a durable outer surface with an inner skin having high air tightness or thermal resistance.
The heretofore known envelope of balloon or airship shape is, however, difficult to inflate and expand to the envelope.
Moreover, because the envelope is formed of flexible material, its hardness is low, and it is difficult to improve the resistance against wind or flight performance. Additionally, it is difficult to control the direction and speed during descent.